Pneumatic rotary tool

Abstract

A pneumatic rotary tool has a housing formed primarily from plastic so that the weight and price of the tool are substantially reduced. The air motor is formed for economic assembly while permitting greater structural stability should the housing deflect under an impact. The tool includes a torque selector which controls the amount of pressurized air allowed to enter the air motor, thereby controlling the torque output of the motor. The user may adjust the torque selector to a number of set positions which correspond to discrete torque values. The tool additionally incorporates early and late stage exhaust ports, so that backpressure within the air motor does not slow motor rotation or decrease tool power.

Description

BACKGROUND OF THE INVENTION[0001]This invention generally relates to pneumatic rotary tools and more particularly to an improved pneumatic rotary tool having a plastic housing and a variable torque design for efficient use of pressurized air.[0002]The invention is especially concerned with a powered tool that rotates an output shaft with a socket for turning a fastener element such as a bolt or nut. Tools of this type are frequently used in automotive repair and industrial applications. Conventionally, pneumatic rotary tools comprise a metallic outer housing with multiple metallic internal parts. These tools are strong and durable due to their metallic construction, although the all-metal construction makes them both somewhat heavy and costly. Pressurized air flowing through the tool powers tools of this type. As the air expands within the tool, it induces motion of an internal motor, powering the tool.[0003]It is an aim of tool manufacturers to provide a pneumatic rotary tool that ...

AI Technical Summary

Benefits of technology

"The present invention provides a pneumatic rotary tool that is lighter, cheaper, and more comfortable to grip. It has a plastic housing that resists misalignment of internal components under impact. The tool has a plastic housing that fixes components without fasteners, is comfortable to grip, and reduces back pressure on the motor. The air motor regulates torque between four discrete levels adjustable by the user. The tool has a torque selector and a grip with a soft material outer layer for better control and comfort. The method of assembly involves engaging end caps with the support sleeve and the Maurer Mechanism casing, and using bolts to compress the parts and hold them in proper alignment within the tool."

Problems solved by technology

These tools are strong and durable due to their metallic construction, although the all-metal construction makes them both somewhat heavy and costly.

One difficulty in the design of such a tool is the reduced rigidity of plastic as compared with a strong metal, such as steel.

For instance, should a plastic tool fall against a hard surface, a metallic air motor inside the tool may shift and become misaligned, or canted, with respect to the housing and the output shaft, rendering the tool unusable.

This problem has led tool manufacturers to create complex internal motor casings designed to inhibit the motor from canting in the housing.

The cylinder, back head and bore are of unitary construction, making a closed end cylinder significantly more difficult to manufacture.

Therefore, these casings are expensive to manufacture, which may mitigate the cost benefit of using lighter and less costly materials, such as plastic, for other parts.

Such a design is inefficient because it uses the maximum flow of pressurized air to power the tool, while operating below its maximum power.

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